linux-kernel - Re: [RFC PATCH 00/21] crypto: consolidate and clean up compression APIs

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Message-ID: <ZMOQiPadP2jggZ2i@gondor.apana.org.au>
Date:   Fri, 28 Jul 2023 17:55:20 +0800
From:   Herbert Xu <herbert@...dor.apana.org.au>
To:     Ard Biesheuvel <ardb@...nel.org>
Cc:     linux-crypto@...r.kernel.org, Eric Biggers <ebiggers@...nel.org>,
        Kees Cook <keescook@...omium.org>,
        Haren Myneni <haren@...ibm.com>,
        Nick Terrell <terrelln@...com>,
        Minchan Kim <minchan@...nel.org>,
        Sergey Senozhatsky <senozhatsky@...omium.org>,
        Jens Axboe <axboe@...nel.dk>,
        Giovanni Cabiddu <giovanni.cabiddu@...el.com>,
        Richard Weinberger <richard@....at>,
        David Ahern <dsahern@...nel.org>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Steffen Klassert <steffen.klassert@...unet.com>,
        linux-kernel@...r.kernel.org, linux-block@...r.kernel.org,
        qat-linux@...el.com, linuxppc-dev@...ts.ozlabs.org,
        linux-mtd@...ts.infradead.org, netdev@...r.kernel.org
Subject: Re: [RFC PATCH 00/21] crypto: consolidate and clean up compression
 APIs

On Tue, Jul 18, 2023 at 02:58:26PM +0200, Ard Biesheuvel wrote:
>
> Patch #2 removes the support for on-the-fly allocation of destination
> buffers and scatterlists from the Intel QAT driver. This is never used,
> and not even implemented by all drivers (the HiSilicon ZIP driver does
> not support it). The diffstat of this patch makes a good case why the
> caller should be in charge of allocating the memory, not the driver.

The implementation in qat may not be optimal, but being able to
allocate memory in the algorithm is a big plus for IPComp at least.

Being able to allocate memory page by page as you decompress
means that:

1. We're not affected by memory fragmentation.
2. We don't waste memory by always allocating for the worst case.

Cheers,
-- 
Email: Herbert Xu <herbert@...dor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt